Client devices, including mobile communication devices (also referred to herein as mobile devices) or personal computers, may run on an operating system and/or use software applications that process data relating to one or more dates. For example, a device may run a calendaring application that includes the capability of maintaining a schedule of calendar events for one or more users. Calendar events may include meetings, conference calls, Internet conferences or “webinars”, activities, holidays, etc. Calendar events may have a designated date or dates. Information relating to one or more dates (such as the date(s) of a calendar event) may be shared between devices. For example, a user at one client device may schedule a calendar event and send out an invitation message to one or more recipients. Recipients of the invitation who accept the invitation may then have that calendar event scheduled in their calendar, and the recipient may be considered a participant of the calendar event.
It is possible that one or more participants for a calendar event may be located in different time zones. A time zone is a region in which local time is uniformly defined. Local time may be defined, for example, by a given offset with respect to Coordinated Universal Time (UTC). The local time for one or more calendar event participants in a first time zone may be different than the local time for one or more other participants in a second time zone. Furthermore, a participant may move from one time zone to another, thereby changing the local time for that participant. Accounting for different local times for different participants may present a challenge for maintaining consistent and accurate start and end times for calendar events scheduled in a calendaring application. For example, when Daylight Savings Time (DST) is not in effect, Eastern Standard Time (EST) is five hours behind UTC and Pacific Standard Time (PST) is eight hours behind UTC. Therefore, if a first client device schedules a meeting at 3:00 pm EST and sends an invitation to a client device in the PST time zone, the PST client device may need to schedule the meeting at 12:00 pm PST.
Time zone identifiers (IDs) may be used in an electronic communication system (such as a wireless communication system) to designate time zones. A given time zone ID may correspond to a set of time zone rules that define a local time, relative to UTC, for a time zone designated by the time zone ID. The rules for a time zone may include rules that are dependent on the date. For example, DST may dictate that, during DST, the local time is offset by a certain number of minutes (e.g. one hour) for a certain portion of the calendar year with respect to the remainder of the year. The start and end dates of DST may vary from time zone to time zone. Time zone rules, such as DST rules, for a given time zone may change from time to time. By way of example, a country's government may set and change time zone rules from time to time. A government may set the dates at which DST for a particular time zone begins and ends for a given year. A new time zone ID may be created for use in a computing system when the rules for a time zone have been altered or updated, where the new time zone ID corresponds to the updated time zone rules.